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How does unequal sample size affect power?
When sample sizes are equal, the inequality of variances across the two groups will not impact the conclusions drawn from these tests. If unequal sample sizes are paired with unequal variances, this can result in dramatic differences in power and inflated or reduced type I error rates.
Can you run an Anova with unequal sample sizes?
You can perform one way ANOVA with unequal sample sizes. You must consider the assumptions of Normality, equality of variance and independence ( that mentioned by Saigopal ) before using ANOVA and in a case of not correct assumption then you must use non-parametric test ( Kruskal-Wallis test ).
When would you use a MANOVA?
MANOVA can be used when we are interested in more than one dependent variable. MANOVA is designed to look at several dependent variables (outcomes) simultaneously and so is a multivariate test, it has the power to detect whether groups differ along a combination of dimensions.
Which is the minimum sample size for MANOVA?
Since 74 is not divisible by 4, the number of groups, if we require a balanced model, then the minimum sample is 76, the next highest number larger than 74 that is divisible by 4. Real Statistics Data Analysis Tool: The Real Statistics Resource Pack also provides a Power and Sample Size data analysis tool that supports One Factor MANOVA.
How to calculate the statistical power of MANOVA?
MANOVA_POWER(f n, k, g, ttype, alpha, iter, prec) = the statistical power for one-way MANOVA where the sample size is n, the number of dependent variables is k , the number of groups is g and the effect size is f, where f = the partial eta-square effect size if ttype = 1, f = eta-square if ttype = 2 and f = Pillai’s V if ttype = 3.
When to use MANOVA vs.separate ANOVA?
If a researcher plans to only use dependent variables that are uncorrelated, there is little advantage for using MANOVA. Moreover, with uncorrelated criteria and relatively small sample size, MANOVA may be at a disadvantage to separate ANOVAs in terms of statistical power.
When are unequal sample sizes are and are not a problem in ANOVA?
So if you have equal variances in your groups and unequal sample sizes, no problem. If you have unequal variances and equal sample sizes, no problem. The only problem is if you have unequal variances and unequal sample sizes.